Many space-based science missions require “next generation” on-board processing capabilities to meet the specified goals of each mission. These missions use advanced instrumentation systems, such as laser altimeter, radar, lidar, and hyper-spectral instruments, which all require advanced on-board processing capabilities to facilitate the timely conversion of earth science data into earth science information. Currently available processing systems do not have the processing power required by these advanced information systems. Both an “order of magnitude” increase in processing power and the ability to “reconfigure on the fly” are required to implement algorithms that detect and react to events, to produce data products on-board for applications such as direct downlink, quick look, and “first responder” real-time awareness, to enable “sensor web” multi-platform collaboration, and to perform on-board “lossless” data reduction by migrating typical ground-based processing functions on-board, thereby reducing on-board storage and downlink requirements.
The SpaceCube™ is a Field Programmable Gate Array (FPGA) based on-board science data processing system developed at the NASA Goddard Space Flight Center (GSFC). The goal of the SpaceCube™ program is to provide one to two orders of magnitude improvements in on-board computing power while lowering relative power consumption and cost. The SpaceCube™ design strategy incorporates commercial radiation-tolerant FPGA technology and couples it with an upset mitigation software architecture to provide “order of magnitude” improvements in computing power over traditional radiation-hardened flight systems.
“On-the-fly” reconfiguration is a term describing the need to change computer programs and/or FPGA configuration and programming data after the board is manufactured or while in space. Typical FPGA based processing systems put much of the configuration and programming data in read only memory which can be programmed or burned only once when the processing system is manufactured, thereby limiting the amount of programming and configuration that may be modified later while the system is in use. Flash memory is a type of reprogrammable non-volatile memory device that offers some of the data retention advantages of read only memory (ROM) or programmable read only memory (PROM) while also having the ability to be reprogrammed. A flash memory device or “flash” is an electronic non-volatile computer memory device that can be electrically erased and reprogrammed. Flash memory is usually referred to by the type of logic gates used to implement the storage elements which are typically NAND or NOR gates. For example, NAND Flash is a flash memory device using NAND gates to store data. Flash memory provides a number of advantageous properties, such as operating on very low power. However, flash memory devices are not without their disadvantages. For example, flash memory devices may be influenced by exposure to radiation present in space flight. Prolonged exposure to radiation can reduce the overall lifespan of the devices and exposure to radiation can also result in single event latchup (SEL) causing the flash devices to draw excessive amounts of current, which, if left unchecked, can damage the devices or drain power from other systems.
Accordingly, it would be desirable to provide low power switching circuitry suitable for space-based flight and missions that addresses at least some of the problems identified above.